Electronic piano



May 9 1951 H. J. SABINE 2,983,177

ELECTRONIC PIANO Filed May 23, 1958 LZEUZLQE United States Patent O ELECTRONIC PIANO Hale J. Sabine, Glen Ellyn, Ill., assignor, by mesne assignments, to Meridan Corporation, Chicago, Ill., a corporation of Washington Filed May 23, 1958, Ser. No. 737,313 A 22 Claims. (Cl. 84-1.16)

This invention relates generally to an improved electronic piano, and more specifically to an improved string frame assembly incorporated therein.

Although the principles of the present invent-ion may be included in various musical instruments, a particularly useful application is made in an electronic piano of the lightweight type which can be sold at a somewhat lower price than conventional pianos.

Broadly speaking, electronic pianos'are old and known in the art. These pianos have had various faults or difticulties, one of which is an excessive size and weight, and another of which is that the piano has not produced a tone which is the same as that of a conventional piano.

Accordingly, it is a principal object of the instant invention to provide a low cost electronic piano having tone quality comparable to a standard piano.

It is a further object of the instant invention to pro- 16, the speaker 17, the cabinet 11, the hammer 13, and the pickup 15.

Referring now to Figure 2, the details of the string frame assembly are shown in greater detail. The string frame is provided with a plurality of strings 14 which are each secured at one end to a hitch pin and at the other end to a tuning pin 21. The frame 12 has a bridge or bearing edge 22 adjacent to the tuning pins 21, the bearing edge 22 being straight in the instant embodiment. The frame 12 also has a second bridge or bearing edge 23 adjacent to the hitch pins 20. The bearing edges 22 and 23 are spaced apart so as to jointly define the length of the speaking or vibrating portion of each vide an electronic musical instrument of the pianoforte type, the components of which have a minimum size and weight.

A still further object of the present invention is to provide an electronic piano having miniature, length strings, having a tone quality comparable to that of 41 inch strings.

Many other advantages, features and additional objects of the present invention will become manifest to those versed in the art upon making reference to the detailed description and the accompanying sheet of drawings in which a preferred structural embodiment incorporating the principles of the present invention is diagrammatically shown by way of illustrative example.

On the drawing:

Figure l is a side sectional view of a piano equipped with a string frame assembly provided in accordance with the principles of the present invention, the string frame being sectioned along line I-I of Figure 2;

Figure 2 is a front view of the string lframe assembly shown in Figure 1; and

' Figure 3 is an enlarged sectional view of a preferred modification of a portion of the structure shown in Figure 1.

As shown on the drawing:

The principles of the present invention are particularly useful when embodied in an electrical musical instrument or piano such as illustrated in Figure 1, generally indicated by the numeral 10. The piano 10 includes a cabinet 1'1 supporting a string frame assembly 12 and an action assembly diagrammatically illustrated by the hammer 13 for exciting a string 14 of the string frame assembly 12. An electrical pickup 15 of the electromagnetic type is also included in the string frame assembly 12, and communicates electromechanically with the strings for converting the vibrations thereof into electrical signals. The pickup 15 also communicates electrically with an electronic amplifier 16 which drives a speaker 17, both supported by the case 11. Conventional structure may be utilized for each of the components not described in detail in the instant specication, such as the amplifier of the strings 14.

The frame 12 has been provided with a number of strings 14 which corresponds exactly to the number of notes in the series which the instrument 10 is to provide. Thus, one feature of Ithe instant invention is that only one string is provided per musical note.

The assembly illustrated in Figure 2 has `88 strings representing the quantity required for a full scale piano having a standard keyboard. Each of the tuning pins 21 is so adjusted that the strings 14 are tuned to provide the equal tempered chromatic scale such as as one with a standard pitch for each string. In the specification and claims hereof, each string is referred to by the name of the note as adopted by the American Standards Association in 1936, such names appearing in the Handbook of Chemistry and Physics, 39th Edition published by the Chemical Rubber Publishing Company. The lowest pitched string is designated as A0, then Alto, B0, C1, Citl, etc., terminating with C8 as being the string for the uppermost note.

It will be noted that the lower bridge or bearing edge 23, which is adjacent to the hitch pins 20, comprises three straight segments. Each of these segments includes over twenty-four strings, and hence includes over two octaves. The center segment of the bearing edge 23 and the segment adjacent to the shortest strings each are so constructed that the speaking portions of successively adjacent strings are of successively shorter lengths, and in that each of these segments is linear, each of the adjacent strings within each of the segments differs in length from its adjacent strings by a like increment. More specically, the upper 28 strings, used for notes between A5 and C8 inclusive differ from those adjacent to each other by a like amount, while the next lower pitched 28 strings used for notes between F3 and Git inclusive also differ from adjacent strings in speaking length by a like amount.

One of the advantages in having the bearing edge or bridge 22 as a straight line is that another feature of the instant invention provides that the hammer 13 shall engage the speaking portion of each of the strings 14 above A2 at a point not over 1/1 inch from the bearing edge 22, and below E2 at a point not over 1% inches from the bearing edge 22. For the notes F2 to A2 inclusive, the limit point varies uniformly from 11,(2 inches to 1/4, inch. Excellent results are achieved when the strike points are within the foregoing ranges, the exact point being largely a matter of personal tonal preference. Thus a uniform strike line is achieved for a set of strings by the straight bridge or bearing edge 22.

The pickup 15 is disposed generally adjacent to the bearing edge or bridge 23. More specitically,- for the lengths of strings disclosed herein, the pickup 15 is preferably disposed about one inch from the bearing edge 23 for the rst five strings representing the notes A0 to Ctl inclusive. For the next 27 strings representing the notes D1 to E3 inclusive, the pickup is preferably disposed about 31/2 inches which is one-sixth the length of the speaking portion from the bearing edge 23. For the next 28 strings representing the notes ,F3 to Gils, inclusive, the pickup is preferably disposed 'about 3% inches from the bearing edge 23 for F3, and about 2 inches from the bearing edge 23 for Git, and varying uniformly therebetween. I'his variation is from Ms to 1;/3 the speaking length.' For the top 28 strings representing the notes A5 .to C3 inclusive, the pickup is preferably disposed about Y2 inches or Vs the speaking length from the bearing edge 23 for A5, and at' the midpoint of the Cs string which is 3% inch from the bearing edge 23. -Thus while there is a variation in pickup location to obtain the most pianolike tone,.the variation is gradual to thereby avoid discontinuities of type of sound as a scale is being played. Certain wound strings tend to produce a type of static when vibrated adjacent to a magnetic pickup, `a phenomenon known as the Barkhausen Effect. -In the instant piano, this effect is substantially absent. However, for

'the lowest five notes, the pickup must be disposed close to thebearing edge 23, as described above, to avoid this problem. v

Conventional pianos employ three strings and a sounding board to obtain therequisite volume. The omission of the resonating sounding board coupled with electrical amplification is suggested by Miessner in his U.S. Patent No. 2,187,612. While Miessner eliminated one string, he found it necessary to use two strings per note, one being damped. His undamped string has a relatively long decay time and his damped string has a much shorter decay time.V By superimposing the sounds from the two strings, he achieved a decay in loudness which tended to simulate the loudness decay in a conventional piano achieved by the sounding board.

I have likewise omitted the sounding board and have oiset the loss of volume by electrical ampliiication. However, I employ only a single string per note coupled with a voicing or damping means which even more closely simulates the loudness decay effected by conventional sounding boards. Y

To this end, I have inserted a damping or voicing member 25 intermediate the string 14 and the bearing edge 23, remote from the hammer strike line. Since I have desired to match the tone of the instant piano quite closely to that of a conventional piano, I have omitted such damping member from the strings used for about the lowest two octaves, for example below the note C3 as shown in Figure 2, because the effect sought to be simulated is not noticeably achieved by sounding boards of conventional pianos. The damping or voicing member 25 comprises la soft material, such as a resilient plastic or rubber. For convenience, I have illustrated the member 25 as being a short tubular segment which closely lits the string, the length of the speaking portion thereof being delined at a point on the string against which the member 25 engages. By this structure, a tone is produced which simulates that previously obtained by the use of three strings with a sounding (and damping) board.

Where the material from which the voicing member 25 is subject to taking a set or being cut by the piano wire, and when a structure is desired that is more readily adjusted, the member 25 may be replaced by a voicing or damping member 26 shown in Figure 3. The member 26 represents the preferred form of construction, but is separately shown for clarity of illustration.

The member 26 includes a bracket 27, a plate 29, and a strip of damping material 31.Y The bracket 27 is securely attached to the frame assembly 12 adjacent to the bearing edge 23, such as by a plurality of screws 28 extending through a hole in the bracket 27. The size and shape of the screw hole in the bracket 27 aord a degree of adjustability. The bracket 27 has a portion 27a extending angularly therefrom which supports the loading plate 29 Vin a planeparallel to and/spaced from the strings 1,4. 'Ihe plate 29extends along the length of the bearing edgeV 23 and overlies a group of the strings 14. The plate 29 is secured to the portion-27a such as by a plurality of screws 30 each extending through a hole therein, which holes afford adegree of adjustability. 'I'he strip of felt 31 is disposed intermediate the plate 29 and the strings 14, and is held thereagainst by the plate and bracket. By this structure, the backing force on the felt and the distance which the felt overlays or extends along the speaking portion of the string 14 may be selected. The exact position has an eiect on the tone produced, the idealV effect being a matter of personal preference.

It isv well known that tension, mass per unit length, and speaking lengthV determine the basic or fundamental frequency of a string. It is also well known that mass per unit length can be increased by applying a close winding or overlay of copper over a piano-wire. However, the various combinations which can be mathematically obtained to produce a given pitch do not necessarily produce a satisfactory result.

Byway of example, a typical good quality upright piano employs' strings having a length of 41 inches and a tension of pounds for a given diameter. It is known that this combination produces a pleasant piano type vibration. It is also known that if the string length is increased up to at least 44 inches, or more, and provided with a 150 pound tension, a combination results which produces a top quality type of vibration such as is used in a premium quality piano. -It is also well known Vthat if the string length is reduced to 36 inches, tension being retained at 150 pounds to obtain theproper pitch for a given sizerwire, a somewhat lower quality of vibration is produced, whichris usable only in competitively priced pianos. 'I'hus it is known that further reduction in, string length without sacrifice of toneis considered impracticalif not impossible, heretofore. e In the foregoing known examples, even though Vall the strings are tuned to the same frequency, the pleasantness is notV equal.- This difference is due to a difference in harmonic content. The harmonic frequencies present are effected by the-modulus of elasticity of the string'material andthe diameter of the Wire or string. vThe amplitude ofthe harmonics is determined by the strike point, the hammer impact force, and the hammer material. Heretofore, vthe strike point has typcallyvaried from 6 inches from the end of the A0 string to 1/s inch from the end of the vCf, string, with only the strings above E, being less than 1A inch. Y

I have discovered that the most significant factor in Ydetermining pleasantness is the factor of which frequencies are present rather than their amplitude. Thus if the most desirable harmonics'are'present and the least desirable ones are absent, pleasantness of tone can be achieved. In the instant invention, for comparison purposes, I have employed a good quality commercial piano having strings of a 41 inch length as a comparison or standard.

By extensive analytical approach, I have found that there is no mathematical relation or formula for pleasantness but by extensive experimentation coupled with many failures, I have obtainedpleasantness at lower lengths and tensions thanhave been done heretofore. I have done this for all of the notes in the standard 88-n`ote keyboard.

Since I have been able to reduce tension somewhat the tendency for the resulting piano to go out of tune is somewhat decreased, and the need for substantial mass and rigidity of the string Yframe is decreased. When the length has been reduced, I have found that the overall size of the piano can be reduced. Size and weight has been further reduced by the omission of the conventional sounding board which has been replaced by the electro-Y magnetic pickup'operating in accordance with known principles. The resulting instrument is dramatically smaller and lighter than has been previously thought possible, without sacrifice of tone quality, Vthe quality obtainedV being about the same as that of a conventional piano having 41 inch strings tensioned at 150 pounds.

I have found that tension canbe reduced to a valuevas low as three pounds without sacrifice of quality, for ce1'- tain notes. However, I have found that an entire series of 88 notes may be achieved using tensions between 5 and 23 pounds, the average tension being about 15 pounds. This has been accomplished using strings having a speaking length between 21 and 11/2 inches, their average length being 14 inches for the 88note series. Where a single string is used per note, the total force produced by the strings tension is less than one ton, being on the order of 1400 pounds. In general, I have found that tension can be varied a good deal without impairment of tone quality, any given string which is satisfactory being usable with maximum and minimum tensions having approximately a four-to-one ratio.

While overlaying a wire with two layers of closespiral-Wound Wire increases the mass per unit length, it also increases the natural damping of the string and renders the harmonic content somewhat unpredictable. In particular, non-integral harmonics appear which are undesirable, such as the 2.1 harmonic. However, in accordance with the instant invention, it is now possible to use bass strings having a single layer of covering wire for the note Fitl and all the lower notes, the range previously requiring a double overlaycr.

A complete instrument may be constructed in accordance with the principles of my invention if the strings are provided in accordance with the following table:

Core Cover Overall Speak- Ten- N ote String Dia., Dia., Dia., ing sion,

inches inches inches Length, pound inches .Ao-A1 Copper .020 032 084 21 5-20 Wound Piano Wire.

Ain-D142- .018 023 064 21 13-23 En-Az 018 013 044 21 12-21 Ath-Cita-.. .018 .009 O36 21 16-23 a o .016 O09 .034 21 23 Dita Solid Piano 025 21 15 Ez ---do .O23 2l 15 Fa-B'r dn O20 (l) 12-17 Clt-F ,dn 017 (l) 12-17 G4-G5 do .016 (1) 12-17 A5-D5 --.do 015 (2) 12-17 E-Afr do 013 (2) 12-17 Ba-Cn n 012 (2) 12-17 1 For Fs to Gita, reduces linearly from 21" t0 5%. 2 For A@ to Ca, reduces linearly from 5%" to 1%.

Thus, to control the non-integral harmonics so that the pleasantness can be controlled, the above combination of strings is preferred and relatively little deviation therefrom can be accompanied for the lengths selected.

Although various minor modifications might be suggested by those versed in the art, it should be understood that I Wish to embody within the scope of the patent warranted hereon all such embodiments as reasonably and properly come within the scope of my contribution to the art.

I claim as my invention:

l. A musical instrument comprising a frame, a plurality of dierently tuned strings mounted on said frame, a pair of spaced bridges operatively associated with each string, and a voicing means in contact with each string and extending from one bridge thereof a limited distance along said string.

2v. A musical instrument for the production of a series of notes below E7 comprising: a string frame, a plurality of differently tuned strings mounted on said frame, said frame having a pair. of spaced bridges operatively associated With each string, and thereby defining the length of the speaking portion of each string, one of said bridges comprising a straight line, a hammer operatively associated with each string and being engageable with the speaking portion thereof at a point not over one-fourth inch from said one straight bridge, a voicing means in contact with each string remotely from said hammer of each string and extending from the other of said bridges on said strings one-sixth the length of said speaking portion from said other of said bridges, and operatively associated with and responsive to vibration of strings tuned between F3 and Gi5 inclusive at a point varying uniformly from one-sixth to one-third the length of said speaking portion from said other of said bridges.

3. A musical instrument for the production of a series of notes below E7 comprising: a string frame, a plurality of differently tuned strings mounted on said frame, a pair of spaced bridges carried by said frame and operatively associated with each string, said bridges defining the length of the speaking portion of the strings, means including a hammer operatively associated with each string and engageable with the speaking portion thereof at a point not over one-fourth inch from one of said bridges, and a voicing means in contact with each string and extending from the other of said bridges a limited distance along said string.

4. A musical instrument for the production of a series of notesibelow E7 comprising: a frame, a plurality of differently tuned strings mounted on said frame, a pair of spaced bridges on said frame operatively associated with each string and defining the length of the speaking portion of each string, one of said bridges comprising a straight line, hammer means operatively associated with each string and engageable with the speaking portion thereof at a point not over one-fourth inch from said one straight bridge, and a voicing means in contact with each string and extending from the other of said bridges a limited distance along said string.

5. A musical instrument comprising: la frame, a plurality of diierently tuned strings mounted on said frame, a pair of spaced bridges carried by said frame and operatively associated with each string and deiining the length of the speaking portion thereof, electrical means operatively associated with strings thereof tuned between El and E3 inclusive at a point on said strings one-sixth the length of said speaking portion from one bridge thereof and responsive to vibration thereof, electrical means operatively associated with strings thereof tuned between F3 and Git5 inclusive at a point varying uniformly from one-sixth to one-third the length of said speaking portion from said one bridge and responsive to the vibration of such strings, and a voicing means in contact with each string and extending from said one bridge thereof a limited distance along said string.

6. A musical instrument comprising: a frame, a plurality of differently tuned strings mounted on said frame, a pair of spaced bridges carried by said frame and operatively associated with each string and deiining the length of the speaking portion thereof, electrical means operatively associated with strings thereof tuned between A0 and Ctl inclusive at a point on said strings immediately adjacent to one bridge thereof and responsive to the vibration of such strings and a voicing means in contact with each string and extending from said one bridge thereof a limited distance along said string.

7. A musical instrument comprising: a frame, a plurality of differently tuned strings mounted on said frame, a pair of spaced bridges carried by said frame and operatively associated with each string and defining the length of the speaking portion thereof, electrical means operatively associated with strings thereof tuned between F3 and Git5 inclusive at a point varying uniformly from one-sixth to one-third the length of said speaking portion from one of said bridges, and a voicing means in contact with each string and extending from said one bridge thereof a limited distance along said string.

S. A musical instrument comprising: a frame, a plurality of differently tuned strings mounted on said frame, a pair of spaced bridges operatively associated with each string, and a voicing means in contact with each string Y 7 and extending from one bridge thereof la limited distance along said string, said voicing meansA extending between each and every one of said strings and said one bridge for an adjacent series of strings. 9. A mrusical instrument comprising: a frame, a plurality of differently tuned strings mounted on said iframe, apair of spaced bridges carried by said frame and opera- Vtively associated with each string, said bridges being so arranged that a series of consecutive strings for two octaves of notes above F3 have speaking portions `defined by said bridges of successively shorter lengths, each of which portions diiers in length from its adjacent strings by the same increment, and a voicing means in contact with each string and extending from one bridge thereof a llimited distance along said string.

10. A musical instrument comprising: a frame, a plurality of diierently tuned strings mounted on said frame, a pair of spaced bridges carried by said frame and operatively associated with each string and defining the length of the speaking portion thereof, said bridges being so arranged that a series of consecutive strings for notes between F3 and Git?, have speaking portions of successively shorter lengths, each of which portions differs in length from its adjacent strings by the same increment, and a voicing means in contact with each string and extending from one bridge thereof a limited distance along said string.

11.A music instrument comprising: a frame, a plurality ofdifferently .tuned strings mounted on saidframe, a pair of spaced bridges carried by said frame and operatively associated with each string and dening the llength of the speaking portion thereof, said bridges being so arranged that a series of consecutive strings for notes between A and C3 have speaking portions of successively shorter lengths, each of which portions differs in length from its adjacent strings Vby the same increment, and a voicing means in contact with each string and extending from one bridge thereof a limited distance along said string. Y l

12. A musical instrument comprising: a-frame, a plurality of differently tuned strings mounted on said frame and having an average tension of about pounds each, a pair of spaced bridges operatively associated with each string, and a voicing means in contact with each -string and extending from one bridge thereof a limited distance along said string. l

13. A musical instrument comprising: a frame, a plurality of differently tuned strings mounted on said frame,

said strings each having a tension less than 23 pounds, a pair of spaced bridges operatively 4associated with each string, and a voicing means in contact with each string and extending from one bridge thereof a limited distance along said string.

14. A musical instrument comprising: a frame, a plurality of diiferently tuned strings'mounted on said frame, said strings having a tension between 5 and 23 pounds each, a pair of spaced bridges operatively associated with each string, and a voicing means in contact with each string -and extending from one bridge thereof a limited distance along said string.

15. A musical instrument comprising: a frame, a plurality of diiferently tuned strings mounted on said frame, said strings having an average speaking `length of about 14 inches, a pair of spaced bridges operatively associated with each string, and a voicing means in contact with each string and extending from one bridge thereof a limited distance along said string.

16. AV music instrument comprising: a frame, a plurality of differently tuned strings mounted on said fname, a pair of spaced bridges carried by said frame and operatively associated with each string and dening the speaking length thereof, said strings each having a speaking length not Vover 21 inches, and a voicing means inv contact with each string and extending from one bridge thereof a limited Vdistance along said string.

assai?? s Y 8 Y v17. A musical instrument comprising: a frame, a plurality of differently tuned strings mounted on said frame, a pair'of spaced bridges carried by said frame and operatively Vassociated with each string, said strings each having a speaking length between 21 inches and 1li/` inches, and a voicing means in contact with each string and extending from one bridge thereof a limited distance along said string.

18. A musical instrument comprising: `a frame, a seri of differently tuned strings mounted on said frame and operative to produce a series of 88 notes between A3 and C3 inclusive, said strings having a combined tension of less than one ton, a pair of spaced bridges operatively associated with each string, and a voicing means in contact with each string tuned above C3 inclusive, and extending from one bridge thereof a' limited distance along said string.

19. A musical instrument comprising: a frame, a seriesV of differently tuned strings mounted on said frame and adapted to produce a series of 88 notes between A3 and C3, said strings having a combined tension of about 1400 pounds, a pair of spaced bridges operatively associated with each string, and a voicing means in contact with each string tuned to C3 inclusive and higher, and extending from one bridge thereof a limited distance along said string.

20. A musical instrument comprising: `a frame, a plurality of differently tuned strings mounted on said frame, said strings being adapted to be tuned to a range of notes inclusive of Fil and C3, a single helical overlaid winding for each of said strings tuned to Fit, and lower,

a pair of spaced bridges operatively associated with each string, 1and a voicing means in contact with each string tuned to C3 and higher, and extending from one bridge thereof a limited distance along said string.

21. A musical instrument comprising: a frame, Va plurality of diierently tuned stringsVV mounted on said frame, 'a pair of spaced bridges carried by said frame and operatively associated with each string and defining the speaking length thereof,ielectrical means operatively associated with strings thereof tuned between D1 and E3 inclusive 'at a point on said strings one-sixth the length of said speakingportion from [oneY of said bridges, and

responsive to the vibration of said strings, and a voicingy means in contact with each string and extending from said one bridge thereof a limited distance along said string.

22. A musical instrument comprising: a frame, a plurality of diierently tuned strings mounted on said frame, said strings being tunable to include the notes E3 and C3, a pair of spaced bridges carried by said frame and operatively associated with each string and dening the lengthV of the speaking portion thereof, a series of hammers operatively associated with said strings, ItheV hammers thereof for the strings tunable below E3 being engageable with the speaking portion thereof at `a point not over one Iand one-half inches from one of said bridges, and a voicing means in contact with each string tunable to C3 `and higher and extending from one bridge thereof a limiteddistance along said string.

References Cited in the le of this patent UNITED STATES PATENTS' 

